Laminated fibrous sheet



Nov. 26, 192%. M. KLIEFOTH 1,737,285

LAMINATED FIBROUS SHEET Filed Oct. 25,. 1928 I lNVEN OR BY I W I $131M, ATTORNEYS Patent ed Nov. 26, 1929 UNITED STATES P TEN OFFICE IzABORATORIES,

INC., OF MADISON, WISCONSIN, A CORPORATION OF DELAWARE LAMINATED FIBROUS SHEET Application filed. October 25, 1928. Serial No. 314,911.

My invention relates to fibrous sheets made by laying down a succession of overlapping folds of moist pulp webs and press ng the overlapping folds into a coherent sheet, as

'5 'described in the application of Howard F. Weiss, Serial No. 139,47 6, filed October 4th, 1926. The present invention consists in an improvement in the method described n that application whereby the pulp web 1s divided 1o into a plurality 'of narrow webs which are laid down together in contacting, side-by-side relation to form a plurality of series of overlapping folds, the folds of the different series, when compressed, interlocking w1th each other to form a single coherent sheet.

It is an object of my invention to provide a multi-ply paper .sheet which is uniform in thickness and density andin which wrinkling of the constituent pulp folds is reduced to a at minimum.

It is a further object of the invention to provide a satisfactory thin multi-ply paper sheet.

It is a still further object of the invention to provide a multi-ply paper sheet which requires a minimum of trimming at the edges. Other objects and advantages will become clear from the following description of my improved process and from the accompanying drawings wherein:

Fig. 1 is a diagrammatic plan view of the apparatus used to make my improved fibrous sheet;

, Fig. 2 is a vertical view on line 2-2 of Fig. 1; i

Fig. 3 is a plan view of a portion of a sheet produced by the apparatus of Figs. 1 and 2 when a wide web is used Fig. 4 is a plan view of a portion of a similar sheet when the wideweb is divided into a plurality of narrow webs;

Fig. 5 is a view of a single fold of pulpweb, showing the distortion to which the pulp is subjected when it is laid down upon a.mov,- ing conveyor;

Fig. 6 is a view of a single fold of pulp showing the wrinkles resulting from distortion; and, I

Fig. 7 is a view illustrating the decreased The wet pulp web' is picked up and carried along on felt 4 and is then pressed by press roll 5. The moist pulp web is picked up by press roll 5 and is removed therefrom by doctor 6. This pulp web may be creped by the doctor or maybe kept smooth, as desired. The pulp web 8 is then carried forward by conveyor belt 7 which is part of a hinged reciprocating looping device which is shown in another position by the dotted lines of Fig. 2. The off-take roll 9 of the hinged looping device works along a guide 10 and distributes the pulp web 8 transversely upon conveyor 11 as shown.

Tightener roll 12 functions to keep conveyor belt 7 taut and directs the return travel of belt 7 along a patch which is at all times as nearly as possible of the same length as the forward path. The pulp web 8 is deposited transversely upon the conveyor 11 in a succession of overlapping folds, adjacent individual folds being spaced from each other in the direction in which conveyor 1 travels. The non-folded side edges of adjacent indi vidual fold sections are at an angle to each other as illustrated by Fig. 3. Conveyor 11 carries the succession of overlapping folds through a continuous press 13, which may be in the form of press rolls.- This operation compresses the loosely piled overlapping folds into a coherent sheet. The sheet may continue through drier 14, side trimmer 15 and cutter 16.

For economical operation, the character of the moist pulp web, as it leaves the wet machine, is fixed within fairly narrow limits. The property, known as freeness, of the pulp fibres determine the p at which water 25 requires subsequent trimming. As the speed will (pass through thescreen 6? cylinder moul 2 and leavea web behind and also de before further passage of water is effectually stopped. The thickness of the pulp web and the rate at which it is formed are, therefore,,.

quite definitelyfixed and the most economical method of increasing output is to increase the width of the web.

i In the formation ofa single fold section,"

conveyor belt 7 may be consldered'as laying down a rectangle 17 of moistpulp web, as

' illustrated in Fig. 5. The movement of conveyor 11, however,

tangle 17 into that of a rhomboid 18. The result is that one diagonal dimension, ad, is increased to ad, while the other diagonal, be, is decreased to be. The pulp is stretched along the longer diagonal andthere is an ex cess along the shorter diagonal. The result is thatwrinkles are formed parallel to the a longer diagonal, as illustrated in Fig. 6. Fur

thermore, a twist is given the web at the folded edge which resultsin further wrinkles and a folded edge which not straight andwhich of conveyor 11 increases each successive fold is laid down at a greater an le to the one pre-' ceding it. In a very thin s eet, for instance, one which has the thickness of only two webs, conveyor 11 travels very fast anddistortion and the wrinkling effect is greatly augmented. Furthermore, it is in the thin sheets that the wrinkling effectsare most noticeable and objectionable. The sheet may be subsequently pressed to a uniform thickness but the density is not uniform and the effect remains in the resence of dark veins and the appearance o wildness.

I have found that if the wide web is divided into a-plurality of narrow webs, the

folds are laid down smoothly, wrinkles are absent, and the folded edges are straight and follow the side edges of the sheet closely, making less trimming necessary. Fig. 7 illustrates the fold shown in Fig. rafter it has been cut in half lengthwise. In this case the distortion of the rectangle into a rhomboid results in dimensional changes in the diagonals of approximately only one half the magnitude of the changes resulting when a wide web is used. Further division of the web results in greater decrease in dimensional distortion andresulting strain and wrinkles. No set rule for maximum allowable width of web can be laid down. The speed of the conveyor 11, the speed of belt 7, the thickness of the pulp web, are all factors which affect necessa'ryto divide it into sections eight inches wide.

Division of the web webs may less than into a plurality of .mould, as by gluing. The cylinder mould may be made in sections. The wide web may be cut into strips orribbons after it is formed distorts the shape of recby causing it to come into contact with a suitable cutting edge such as a sharpvedged disc pressing against and traveling at the same speed as press roll- 5. As the specific means for dividing the web forms no part of my invention, and as numerous devices well known to those skilled in the art may be employed for this purpose, I have not illustrated suc means in the drawings.

be accomplished by a num- Throughout the claims the term folds is used to define, not only the folded'edge, .but the entire overlapping portions formed by each reciprocation of'the looping device,

and the term edge when used in conjunction with ffolds is intended to mean either the folded edge or loop, or the nonfolded side edge of the portion of the web forming the folds.

I claim 1. The step'in the method of making a fibrous sheet of uniform thickness which comprises laying down a plurality of narrow moist pulp webs simultaneously in contacting side-by-side relation transversely upon a moving conveyor to form a plurality of overlapping folds of pulp webs.

2. The steps in the method of making a fibrous sheet of uniform thickness which comprise cre ing a plurality of narrow moist pulp webs, aying said creped webs in adjacent side-by-side relation transversely upon a moving conveyor to form a plurality of overlapping folds of pulp webs.

3. The method of making a fibrous sheet of uniform thickness which comprises laying down a plurality of narrow moist pulp webs in contacting side-by-side relationv transversely upon a moving conveyor to form a plurality of overlapping folds of pulp webs and pressing said folds into a coherent sheet.

4. The method of making a fibrous sheet of uniform thickness which comprises laying down a plurality of narrow, moist pulp webs in contacting side-by-side relation transversely upon a moving conveyor to form a plurality of overlapping folds of pulp web, pressing said folds into a coherent sheet, and drying said pressed sheet. a

5. The method of making a fibrous sheet of uniform thickness which comprises forming .a suspension of pulp, forming a plurality of narrow webs from said pulp in contacting si-de-by-side relation, laying down said webs together transversely upon a moving conveyor to form a plurality of overla ping folds of pulp webs, and pressing said olds intoa coherent sheet.

6. The method of making a fibrous sheet of uniform thickness which comprises dividing a moist pulp web into a plurality of narrow webs, laying down said narrow webs together transversely upon a moving conveyor in contacting, side-by-side relation to form a plurality of overlapping folds, and pressing said folds into a coherent sheet.

7. As an article of manufacture, a fibrous sheet comprising a plurality of overlapping folds of a plurality of narrow pulp webs in contacting side-by-side relation, said folds having edges extending in transverse relation to the machine direction of the sheet, said edges being spaced from each other in the machine direction of the finished sheet.

8. As an article of manufacture, a fibrous sheet comprising a pluralityof overlapping folds of a plurality of narrow creped pulp websin side-by-side relation, said folds having edges extending in transverse relation to the machine direction of the sheet, said edges being spaced from each other in the machine direction of the finished sheet. I

In testimony whereof I aflix my signature.

MAX KLIEFOTH. 

